Unusual Situation -- Advice and Tips for First Days Welcome!

So here's my situation: I'm fostering (possibly adopting) a dog I already know. He was my next door neighbor's dog and they had to surrender him at a time when I couldn't take on another dog (three of my own plus committed to foster another already at the time). Before he was rehomed, I'd regularly take him with 2 of my dogs to the beach for off-leash swimming and play with our regular dog playgroup that meets there every morning.

So, he was surrendered, adopted and then returned to the rescue -- I'd say he's been away about a year total. I picked him up this morning and it's been tricky following the regular decompression protocol because he remembers me, he remembers the area, he remembers my dogs (except my newest one).

Before he was rehomed, he'd be playing off-leash with me all the time at the beach. But now I'm uncertain how long to wait before letting him off-leash? I picked him up this morning and was relieved he seemed to remember me and was his usual sweet goofy affectionate self. I drove him home without incident and took him for a walk around the neighborhood. He seemed pretty happy and unfazed, taking it all in. I brought my dogs outside to "meet" him, they were barky jerks which I expected lol. I brought him inside and he's currently resting in an area with his dog bed and food/water dishes, separated from my 3 little dogs with a giant baby gate.

What does anyone recommend for how to manage this situation? Any tips/suggestions?

My plan is to just let him rest today, just take him out for potty breaks, then start taking him to the beach every morning starting with tomorrow. He's an extremely high energy labradoodle who loves to run and play with the other dogs there. My 3 little ones are varying levels of hostile, but I'm sure in time they'll adjust to having him around, especially when they're all at the beach together.

Another element: my neighbors and their kids are understandably excited to spend time with him again and take him for hikes and such. I'm all for it -- but is there a downside here I'm not aware of, from the dog's perspective? Because I can't see a downside here at all, once he understands that he's sleeping at my house, it should only be a good and happy thing for for him, right?